The present invention is directed to an adapter for a twist-lock extension cord, and the like, which extension cord has at one thereof a female plug-end for reception of a male plug-end of an adapter, or the male end of a power tool-cord. Twist-lock extension cords are typically used at construction sites for tools, to ensure that the male plug of the tool-cord cannot accidentally come loose and disconnect. This is achieved by the provision of an offset portion for each one of the three plug-electrodes of the male plug-end of the cord of the power tool. The offset portion of the projections or electrodes of the male plug prevents removal of the male plug from the associated mating female plug-end of the twist-lock extension cord, which is accomplished by simply rotating the male plug in a direction to cause the offset portions to become positioned behind a cooperating member of the cover in which are formed the corresponding openings of the female plug-end of the extension cord through which are inserted and similarly-shaped electrodes of the male plug. Thus, by rotating, or twisting, the male plug, the offset portions of the electrodes are moved behind the members, and thus serve as stops to the removal of the male plug from the female plug of the twist-lock extension cord.
Twist-lock adapters are also available to allow use of a power tool with the twist-lock extension cord if the power tool is not equipped with the twist-lock type of male plug end. The problems with these adapters are that they are removably coupled to the female-end of the extension cord, and thus are are easily lost or stolen, which is commonplace, since these twist-lock adapters are not inexpensive.